Visual ground fault indicator

ABSTRACT

A ground fault testing receptacle comprising a frontal panel incorporating a standard electrical service outlet and a grounding terminal. The panel has a red signal lamp at one side, a white signal lamp at the other side, and a toggle switch below. If the ground line for the premises is normal, the closing of the switch will turn on the white lamp. However, it will turn on the red lamp if the ground line is broken. The signals are conditions for plugging an electrical appliance into the outlet.

[ Mar. 18, 1975 United States Patent [1 1 Kolodziej [54] VISUAL GROUND FAULT INDICATOR FOREIGN PATENTS OR APPLICATIONS 1,176,983 1/1970 UnitedKingdom................324/5l Prinmry E.\'aminerGerard R. Strecker 22 Filed:

[57] ABSTRACT A ground fault testing receptacle comprising a frontal panel incorporating a standard electrical service outlet and a grounding terminal. The panel has a red signal lamp at one side, a white signal lamp at the other side, and a toggle switch below. If the ground line for the 525 5N5 mum 4 4 3 3 ,0" 6 6 6 6 m .1. 3 M5 1 5 m3 w 4 u wk 2 "n C 3 n" S "H" e c "u" n "H" e n r m" cm uh e mmm R "8 mu In C...0 smk UIF HUM m 555 5 UNITED STATES PATENTS premises is normal, the closing of the switch will turn on the white lamp. However, it will turn on the red e n 0m c m am he ac nn a e r w .l F 05 nm n kt w 0C a 1 r. 10 D m s, Hg m n .l d.l 3 H 0 u mm 2 P er mm TUS t mm mm l do XH MXX M M4 257.25% 34334/ 2 .20 3 34 3 e n U S hmflw B t. X n m a 0 m DSWT 00056 3 456677 999999 111111 l 9. oo

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VISUAL GROUND FAULT INDICATOR This invention relates to electric service wiring in buildings and dwellings, and more particularly to devices for protecting the service, appliances and persons using the same. At times conditions in the wiring installation, or interference with the same from outside sources, create a ground fault whose presence does not become known to the user of the electric service, but nevertheless impairs the latter. Another failure often undetected is a defect in an appliance whichcould cause a short when the appliance is plugged in for use, and even create a safety hazard to the person attending the appliance or about to use the same. Thus, failures in service, and hazards which can be very serious and even fatal may exist without revealing their presence, and create a risk when an appliance not known to be defective is connected with a service outlet. Also, in some circuit-protecting devices, their operation depends on a return of electric current through the person handling the appliance, which is an unnecessary and often a dangerous process and should be avoided.

In view of the above situation, it is one object of the present invention to provide a replacement of the common wall outlet in the form ofa testing receptacle which serves both as a service outlet and a test unit for appliances plugged in only when their use is desired, such as electric broilers, fans, heaters and the like.

A further object is to provide a testing receptacle having a lamp which emits a white light when a test switch is closed, to indicate that the ground line is in good order.

Another object is to provide the testing receptacle with a lamp which emits a red light when the test switch is closed. this indicating that the ground line is defective or interrupted.

A better understanding of the invention may be gained by reference to the accompanying drawing, in which a diagrammatic view of the testing receptacle is shown.

Referring specifically to the drawing, denotes a wall panel representing a standard electric service out let, 1] being its socket, l2 and 13 the service terminals, and 14 a ground terminal. These elements are in front of a suitable box (not shown).

A pair of lamps are in view at the top of the panel, the lamp R being red and the lamp W being white. At the bottom is a toggle switch S. The power supply is represented by a negative line 31 connected to a ground line G, and a positive line 32.

In the circuit of the testing receptacle the ground line G is connected to the ground terminal 14. The negative line 31 is connected to the service terminal 12; and the positive conductor 32 is connected to the service terminal 13. A conductor 33 connects one of the terminals of the lamps R and W, and joins the ground line G at 33a. The other terminal of the lamp R is connected to the conductor 31. The terminal 13 is connected by a conductor 34 to one terminal of the switch S, while the other terminal of the lamp W is connected by a line 35 to the other terminal of the switch. A resistance 36 greater than that of the lamp W connects the ground line G with the conductor 35.

Before an appliance is plugged into the socket 11, the ground circuit may be tested to determine its condition. The switch S is closed for this purpose; and the normal condition of the ground is determined if the lamp W lights. The circuit involved in this test comprises the positive line 32, the terminal 13, conductor 34, the switch S, conductor 35, the lamp W, conductor 33 and the ground line G. The lamp and the resistance 36 are in parallelism, with the lamp forming an easier path for the current than the resistance.

When the same test is tried, and only the lamp R lights, this is an indication that the ground is interrupted, such as at a point 0-1. The circuit now comprises the positive line 32, terminal 13, conductor 34, the switch S, conductor 35, resistance 36, ground line G, conductor 33, the red lamp R, and the negative return conductor 31. While the white lamp is a bypass from the circuit just described, it will not light because the resistance of the red lamp R is too high with the resistance 36 in parallel.

When the test is made as first described, and the normalcy of the ground determined, the appliance may be plugged in. In case it does not operate, one fault may be a break or loose connection of the appliance. Another may be a short in the appliance. ln this event the house fuse will blow and cut off the current from the premises.

The, result in the second test is of course a notice that no current is obtainable from the outlet, so that the appliance will not operate when plugged in. Also, the light R is a warning in this event'not to plug in the appliance because if it is defective the house current will be cut off.

It is now apparent that the novel testing receptacle is an important development of the conventional current outlet providing a quick way to test the ground circuit before an appliance is added to the circuit. The testing circuit is incorporated in the conventional outlet panel instead of being a separate unit, and combines with the outlet in compact form. The additions to the house circuit are few, and the apparent change is merely a replacement panel.

I claim:

1. A ground fault indicating receptacle comprising a frontal panel with an outlet presenting a pair of service terminals and a ground terminal, red and white signal lamps mounted in the panel, a switch also mounted in the same and operable to light the white lamp in case of a normalground connection and the red lamp in case of an interrupted ground connection, a resistance element, a circuit for said lamps, resistance element and switch, including a ground line connected to said ground terminal, a grounded negative feed line connected to one service terminal and a positive feed line connected to the other service terminal wherein one terminal of each lamp is connected to the ground line, the other terminal of the red lamp is connected to the grounded negative feed line and said one service terminal, the other service terminal is connected to one side of the switch, the other terminal of the white lamp is connected to the other side of the switch and said resistance element interconnects said other terminal of the white lamp with the ground line.

2. A visual indicating device for a faulty ground connection in a first electrical service outlet circuit comprising a receptacle with two service terminals and. a ground terminal, a grounded negative feed line connected to one of said service terminals, a positive feed line connected to the other of said service terminals, a ground line connected to the ground terminal, and a second circuit comprising a first conductor interconhaving an impedance greater than that of said one lamp,vsaid first conductor being joined to said ground line between said lamps, whereby when said switch is closed, said one lamp will be lighted if the ground line is in order and said other lamp will be lighted if the ground line is faulty. 

1. A ground fault indicating receptacle comprising a frontal panel with an outlet presenting a pair of service terminals and a ground terminal, red and white signal lamps mounted in the panel, a switch also mounted in the same and operable to light the white lamp in case of a normal ground connection and the red lamp in case of an interrupted ground connection, a resistance element, a circuit for said lamps, resistance element and switch, including a ground line connected to said ground terminal, a grounded negative feed line connected to one service terminal and a positive feed line connected to the other service terminal wherein one terminal of each lamp is connected to the ground line, the other terminal of the red lamp is connected to the grounded negative feed line and said one service terminal, the other service terminal is connected to one side of the switch, the other terminal of the white lamp is connected to the other side of the switch and said resistance element interconnects said other terminal of the white lamp with the ground line.
 2. A visual indicating device for a faulty ground connection in a first electrical service outlet circuit comprising a receptacle with two service terminals and a ground terminal, a grounded negative feed line connected to one of said service terminals, a positive feed line connected to the other of said service terminals, a ground line connected to the ground terminal, and a second circuit comprising a first conductor interconnecting the grounded negative feed line and one terminal of a switch, a pair of differently colorEd lamps in series with said first conductor, a second conductor interconnecting said positive feed line and the other terminal of said switch and a resistance element connected to said ground line and to said first conductor in parallel relationship with one of said lamps, said element having an impedance greater than that of said one lamp, said first conductor being joined to said ground line between said lamps, whereby when said switch is closed, said one lamp will be lighted if the ground line is in order and said other lamp will be lighted if the ground line is faulty. 